chicken_code.js

//自我数 (Self number)
//不能由任何一个整数加上这个整数的各位数字和生成的数，称之为自我数。例如：21不是自我数，因为21可以由整数15和15的各位数字1,5生成，即21＝15＋1＋5。
function selfNumber(num){
    for(let i=0;i<=1000;i++){
        if(calc(i) == num)
            return false;
    }
    return true;
}
function calc(num){
    return parseInt(num/10) + num%10 + num;
}
selfNumber(10);



//Write a method to replace all spaces in a string with %20.
function replaceSpace(str){
    let res = "";
    for(let i=0;i<str.length;i++){
        if(str.charAt(i) == " ")
            res += "%20";
        else
            res += str.charAt(i);
    }
    return res;
    //return str.replace(/ +/g,"%20");
}

//手动实现替换函数
function replaceFun(str,target,replacement){
    let res = "";
    for(let i=0;i<str.length;){
        if(isMatch(str,i,target)){
            i+=replacement.length;
            res +=replacement;
        }else {
            res+=str[i];
            i++;
        }
    }
    return res;
}

function isMatch(str,pos,target){
    for(let i=0;i<target.length && i+pos < str.length;i++){
        if(str.charAt(pos+i) != target.charAt(i)){
            return false;
        }
    }
    return true;
}

replaceFun("123 455556 789","5","0")


/**
 * Big Num
 * @param {string} num1
 * @param {string} num2
 * @return {string}
 */
let multiply = function(num1, num2) {
    //判断输入是不是数字
  if(isNaN(num1) || isNaN(num2)) return ''
  let len1 = num1.length,
    len2 = num2.length
  let res = []
  
  //这里倒过来遍历很妙,不需要处理进位了
  for (let i = len1 - 1; i >= 0; i--) {   
    for (let j = len2 - 1; j >= 0; j--) {
      let index1 = i + j, 
          index2 = i + j + 1
      let mul = num1[i] * num2[j] + (res[index2] || 0)
      
      res[index2] = mul % 10

      res[index1] = (res[index1] || 0) + Math.floor(mul / 10) 
    }
  }
    
    //去掉前置0
  let result = res.join('').replace(/^0+/,'')
    
    //不要转成数字判断，否则可能会超精度！
  return !result ? '0' : result
}
multiply("123","45")



//单词去重
function cleanWords(str){
    let arr = str.split(" "),
        res = [arr[0]];
    for(let i=0;i<arr.length;i++){
        if(res.includes(arr[i])){
            continue;            
        }
        else{
            res.push(arr[i]);
        }
        
    }
    return res.join(" ");
}
cleanWords("Joins two or the more arrays, two and arrays returns returns a copy of the joined arrays");